XF86DRIDestroyDrawable are all called directly from DRI drivers using
the new interface. Therefore, prototypes, using available datatypes,
must be available in dri_interface.h. Since the prototypes are
available there, xf86dri.h is no longer needed for
DRI_NEW_INTERFACE_ONLY builds.
interface that are not *strictly* part of the old interface were
changed. Replace GetDrawableInfo type (dri_util.h) with
PFNGLXGETDRAWABLEINFOPROC (dri_interface.h). Wrap __driCreateScreen
(in drivers that use the new interface) with '#ifndef
DRI_NEW_INTERFACE_ONLY'.